Along with rapid development of electronics and information technology, precision components are required to be smaller and more highly integrated, and hence super precise positioning devices have become necessary, which support inspection or superfine processing in the nano order (10−9 m). In addition, in medical or biotechnology research, application technologies by control of proteins or cells have been developed, and hence there are increasing needs for a microscope stage capable of positioning in more precise region. Further, in recent years, together with the demand for higher precision, smaller size and lighter weight of the positioning device and a drive source thereof are also required as objects to be inspected, processed, or measured have become smaller.
As a driving device responding to the needs in such a nano order precise region, an ultrasonic motor using a piezoelectric vibration element as described in Patent Documents 1 to 3 has been developed as an alternative to a conventional electromagnetic motor.
The ultrasonic motor is a driving device based on a drive principle completely different from that of an electromagnetic motor, and has superior features of low speed, high torque, no sound, and high holding power in standstill. In addition, because the transducer has a simple structure, the ultrasonic motor is advantageous for downsizing and is expected as a small actuator.
In general, the ultrasonic motor includes a transducer and a moving body, and functions in a state where a friction contact portion of the transducer is pressed to the moving body with a pressure. In this state, an elliptical motion is generated in the friction contact portion of the transducer so that the friction contact portion sends out the moving body in one way while intermittently pressing the moving body. Working speed of the moving body is controlled by changing amplitude of the elliptical motion.